EXTERNAL RADIATION AND THYROID NEOPLASIA

One hundred years have passed since Roentgen discovered x-rays and 20 years since the National Institutes of Health initiated the first nati onal effort to alert individuals about the risks of childhood radiatio n exposure to the head and neck. Ln the subsequent 20 years, any of th e initial skepticism about the reality of the risks has been dispelled , in part by dose-response analyses of multiple studies. These analyse s also have shown that the risk is of very long duration, persisting t o the present time. To date, radiation-related thyroid cancer seems to have the same natural history as thyroid cancer in other settings. Al though this observation is clinically useful, several areas of uncerta inty in the screening of irradiated individuals and the treatment of r adiation-related thyroid neoplasms still remain.